FrankensteinDid you put a 6.5 in a Camaro? A Duramax in a boat? A Cummins in a Chevy? A Powerstroke in a van? Then you must have a touch of the good Dr. Frankenstein. Post your stories, questions, discussions in here... this is intended to be a place to discuss your questions on how to, what to do, etc...

Ive been talking about a Dmax/Allison/14bolt swap into a 1/2 ton SIlverado RC/SB 2wd for a couple years now. Thanks to my wonderful wife's generosity, I found one for cheap last Sunday and brought it home.... a 1999 Silverado RC/SB 2wd. The truck is completely devoid of options. LOL No A/C, no power options...nothing. Doesnt run, but who cares? Needs some body work, but so what? Frame's good, all electrical works.
My current LB7/5spd will go into this truck. Now shopping for a 2005-2007 Dmax donor for BBT. Found a couple candidates already.

Im not too worried about the actual swap of the motor and trans. Can I use the 1500 trans crossmember with the Allison mount, though?
Radiator and I/C will be interesting, depending if I end up doing the 2" progressive body lift to fit the Dmax core support, or if we section the frame to drop the radiator down in to fit the 1500 support. Taurus fans will be used, so no worries on cooling. Frame will be boxed.
Been wondering about the brakes. If its possible, Id like to remove the ABS system, as long as the brakes will still work.

I havent got a complete plan for is the electrical, though. Will I have to use the lower harness (with the ground leads) from the Dmax or can I use the 1500 one? Since the truck has a manual trans, will I have to swap in an automatic column so the ignition will work correctly? Not sure how Id bypass the clutch interlock.
I will probably end up swapping in a Dmax UBEC, so Im wondering if there is anything inside the truck I will have to add other than the accel pedal?

Any info from guys who have done a swap like this would be appreciated. It'll take a while to put together

Your biggest hurdle will be overcoming the wiring changes from 99-02 to the 03-07. How functional do you want it to be? if your after a bare bones swap, it could be pulled off pretty easily I would think, but it would basically be a race truck. If you want the accesories and such to work, then be prepared to rewire the truck to the 03-07 wiring style and such to make it all work together.

Hey Tom, this should keep you busy for a while.
OK, this is what I am thinking. Plan on the 2 inches at the front for sure. Two reasons, radiator support and the intake horn will hit the hood if you don't lift. The 1500 cross member might need to be fabed but that is one of the easy things.
Someway your 2003 ECM will talk to the 2001 BCM, probably takes some TECH2 and EFI but theTDIguy posted a suburban that someone hacked a LBZ into a 2001. So maybe that can be done because of the slow speed buss that is common. If you don't need all of the normal stuff working it should work
To save a lot of time and wasted effort, get started with the right game plan. PM Eric, he knows the tricks that will get you on the right course.
I read most of your threads over the last few years and I know that you can make it work. I am subscribing. You have helped a lot of folks over the years, so here is an "atta boy" from me.

It will be a neat truck and maybe 1500 lbs lighter.

I note two things from your photos.
That is a nice shade tree, perfect for pulling engines and doing builds. I can see a Frankenstein lurking under the branches.

Your biggest hurdle will be overcoming the wiring changes from 99-02 to the 03-07. How functional do you want it to be? if your after a bare bones swap, it could be pulled off pretty easily I would think, but it would basically be a race truck. If you want the accesories and such to work, then be prepared to rewire the truck to the 03-07 wiring style and such to make it all work together.

Ferm & testdrive, sorry I should have stated this first....I would swap my LB7 engine harness over to an 01-02 in order to better match the red truck electricals. I knew I was forgetting a detail in there. I'm just not sure if there are any other circuits Im going to have to add, and if just running a 2001-02 Duramax UBEC would just be a better idea. BBT would get the LLY or LBZ, which would be a decent swap in itself. Yes, both will be a lot of work. This project isnt going to be finished for a while.

The tree is a Catalpa. Its wood is very soft. Would not be a good candidate for a motor pull. Right now its flowering, and its beautiful.

The truck in the garage is my wife's Blazer. Could you see that thing with a Dmax underhood? LOL Thanks for the encouragement and kind remarks.

For an LB7 it can be donewithout a body lift, but a cowl hood will help alot. Will this be a street rod, or drag truck? If going for a drag truck go bare bones with a stand alone set-up and cut out all of the un needed weight. If it will be a street driver/sleeper, then you've got your work cut out for yeah. I know it can be made to work as osmebody here just did an 03 BURB I eblieve with an LB7 and din't do a body lift with it. I do know that the stock 1500 crossmember will not work as is, but Eric used to have some pics here of how he modded the trans crossmember and motor mounts. Big issues will be that the 1500 truck uses the LS engine saddles which are in a completely differrent location from those of a HD truck. i want to say Eric uses a 6" set-back plate to make the mounts work, and puts about a 4" setback into the trans crossmember as well. Wether you want to go with a drag truck or a sleeper will dictate how much it will take to make it work.

If you're not upping the engine output beyond 660 ft-lbs, and you're not towing anything, then I wouldn't bother with the axle swap at all. Just use a 4L85E and take advantage of the taller axle ratios the 8.625" offers. Especially since the 3.21:1 gears are recently gone from the 14-bolt listings.
If you need the axle swap, then the 2500HD version is a direct bolt-in, but the 3500 version has the spring pads moved inboard. Besides, the 10.5" is overkill for the 1500 frame, which is so thin you'll probably twist it with just 660 TQ and a 4L85E, let alone the deeper-geared Allison. ( 2.482:1 vs 3.10:1 first )
If you do swap axles, plan on needing at least 2" shackles for the rear, even without adding any front-end weight. With the heavier engine, you'll probably need hangers to make it a 4" drop, just to keep the stock rake with un-cut front springs.
I've been running Bell Tech 2" shackles on the rear for 20K miles now, they have an adjustment for just 1". I've had over 3,500# in the bed, no problems from the shackles.

Hmm, 660ft/lbs is a bit conservative....4L85 wont cut it, neither will the stock 10-bolt. The guys keep saying that a 10.5 is overkill, but think....its not the truck Im worried about, rather the engine output. I know the truck is going to twist. Frame will be boxed and possibly a couple more crossmembers (if I can fab a driveshaft loop combo, and also to move the rear shocks to behind the axle). FYI, even our 2500hd's twist slightly under power.

I was planning on using drop shackles. May have to go a bit more severe than that, but wont know til everything is done.
Going to have to explore front spring rates (6.0 A/C springs may work), but that Dmax is going to sink the front right on down no matter what I do.

4L85Es can be built to hold 1400 ft-lbs in a 3000# car, and 1000 ft-lbs in a 4500# car.
The 8.625" 10-bolt is proven to hold 900 HP in a 4000# drag race big-block Camaro on slicks.
Crew-cab front springs will help, the 6.0 is NO heavier than a 4.8 or 5.3.

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